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<title>EVP_PKEY_set1_encoded_public_key</title>
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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
  <li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
  <li><a href="#EXAMPLES">EXAMPLES</a>
    <ul>
      <li><a href="#Set-up-a-peers-EVP_PKEY-ready-for-a-key-exchange-operation">Set up a peer&#39;s EVP_PKEY ready for a key exchange operation</a></li>
      <li><a href="#Get-an-encoded-public-key-to-send-to-a-peer">Get an encoded public key to send to a peer</a></li>
    </ul>
  </li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#HISTORY">HISTORY</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>EVP_PKEY_set1_encoded_public_key, EVP_PKEY_get1_encoded_public_key, EVP_PKEY_set1_tls_encodedpoint, EVP_PKEY_get1_tls_encodedpoint - functions to set and get public key data within an EVP_PKEY</p>

<h1 id="SYNOPSIS">SYNOPSIS</h1>

<pre><code>#include &lt;openssl/evp.h&gt;

int EVP_PKEY_set1_encoded_public_key(EVP_PKEY *pkey,
                                     const unsigned char *pub, size_t publen);

size_t EVP_PKEY_get1_encoded_public_key(EVP_PKEY *pkey, unsigned char **ppub);</code></pre>

<p>The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining <b>OPENSSL_API_COMPAT</b> with a suitable version value, see <a href="../man7/openssl_user_macros.html">openssl_user_macros(7)</a>:</p>

<pre><code>int EVP_PKEY_set1_tls_encodedpoint(EVP_PKEY *pkey,
                                   const unsigned char *pt, size_t ptlen);

size_t EVP_PKEY_get1_tls_encodedpoint(EVP_PKEY *pkey, unsigned char **ppt);</code></pre>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>EVP_PKEY_set1_encoded_public_key() can be used to set the public key value within an existing EVP_PKEY object. For the built-in OpenSSL algorithms this currently only works for those that support key exchange. Parameters are not set as part of this operation, so typically an application will create an EVP_PKEY first, set the parameters on it, and then call this function. For example setting the parameters might be done using <a href="../man3/EVP_PKEY_copy_parameters.html">EVP_PKEY_copy_parameters(3)</a>.</p>

<p>The format for the encoded public key will depend on the algorithm in use. For DH it should be encoded as a positive integer in big-endian form. For EC is should be a point conforming to Sec. 2.3.4 of the SECG SEC 1 (&quot;Elliptic Curve Cryptography&quot;) standard. For X25519 and X448 it should be encoded in a format as defined by RFC7748.</p>

<p>The key to be updated is supplied in <b>pkey</b>. The buffer containing the encoded key is pointed to be <b>pub</b>. The length of the buffer is supplied in <b>publen</b>.</p>

<p>EVP_PKEY_get1_encoded_public_key() does the equivalent operation except that the encoded public key is returned to the application. The key containing the public key data is supplied in <b>pkey</b>. A buffer containing the encoded key will be allocated and stored in <b>*ppub</b>. The length of the encoded public key is returned by the function. The application is responsible for freeing the allocated buffer.</p>

<p>The macro EVP_PKEY_set1_tls_encodedpoint() is deprecated and simply calls EVP_PKEY_set1_encoded_public_key() with all the same arguments. New applications should use EVP_PKEY_set1_encoded_public_key() instead.</p>

<p>The macro EVP_PKEY_get1_tls_encodedpoint() is deprecated and simply calls EVP_PKEY_get1_encoded_public_key() with all the same arguments. New applications should use EVP_PKEY_get1_encoded_public_key() instead.</p>

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

<p>EVP_PKEY_set1_encoded_public_key() returns 1 for success and 0 or a negative value for failure.</p>

<p>EVP_PKEY_get1_encoded_public_key() returns the length of the encoded key or 0 for failure.</p>

<h1 id="EXAMPLES">EXAMPLES</h1>

<p>See <a href="../man3/EVP_PKEY_derive_init.html">EVP_PKEY_derive_init(3)</a> and <a href="../man3/EVP_PKEY_derive.html">EVP_PKEY_derive(3)</a> for information about performing a key exchange operation.</p>

<h2 id="Set-up-a-peers-EVP_PKEY-ready-for-a-key-exchange-operation">Set up a peer&#39;s EVP_PKEY ready for a key exchange operation</h2>

<pre><code>#include &lt;openssl/evp.h&gt;

int exchange(EVP_PKEY *ourkey, unsigned char *peer_pub, size_t peer_pub_len)
{
    EVP_PKEY *peerkey = EVP_PKEY_new();

    if (peerkey == NULL || EVP_PKEY_copy_parameters(peerkey, ourkey) &lt;= 0)
        return 0;

    if (EVP_PKEY_set1_encoded_public_key(peerkey, peer_pub,
                                         peer_pub_len) &lt;= 0)
        return 0;

    /* Do the key exchange here */

    EVP_PKEY_free(peerkey);

    return 1;
}</code></pre>

<h2 id="Get-an-encoded-public-key-to-send-to-a-peer">Get an encoded public key to send to a peer</h2>

<pre><code>#include &lt;openssl/evp.h&gt;

int get_encoded_pub_key(EVP_PKEY *ourkey)
{
    unsigned char *pubkey;
    size_t pubkey_len;

   pubkey_len = EVP_PKEY_get1_encoded_public_key(ourkey, &amp;pubkey);
   if (pubkey_len == 0)
       return 0;

   /*
    * Send the encoded public key stored in the buffer at &quot;pubkey&quot; and of
    * length pubkey_len, to the peer.
    */

   OPENSSL_free(pubkey);
   return 1;
}</code></pre>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man3/EVP_PKEY_new.html">EVP_PKEY_new(3)</a>, <a href="../man3/EVP_PKEY_copy_parameters.html">EVP_PKEY_copy_parameters(3)</a>, <a href="../man3/EVP_PKEY_derive_init.html">EVP_PKEY_derive_init(3)</a>, <a href="../man3/EVP_PKEY_derive.html">EVP_PKEY_derive(3)</a>, <a href="../man7/EVP_PKEY-DH.html">EVP_PKEY-DH(7)</a>, <a href="../man7/EVP_PKEY-EC.html">EVP_PKEY-EC(7)</a>, <a href="../man7/EVP_PKEY-X25519.html">EVP_PKEY-X25519(7)</a>, <a href="../man7/EVP_PKEY-X448.html">EVP_PKEY-X448(7)</a></p>

<h1 id="HISTORY">HISTORY</h1>

<p>EVP_PKEY_set1_encoded_public_key() and EVP_PKEY_get1_encoded_public_key() were added in OpenSSL 3.0.</p>

<p>EVP_PKEY_set1_tls_encodedpoint() and EVP_PKEY_get1_tls_encodedpoint() were deprecated in OpenSSL 3.0.</p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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